Winch pull calculations?

[BHD]

built a winch, (it works fine, but have a use for it where knowing the line pull would be appreciated),

using a 50 to 1 reduction worm drive gear box,
Power is with a reversible eclectic drill only chucked to the input shaft, guessing I allow about 30 foot pounds of torque (max) on the input shaft, (holding the drill from spinning),
the drum is about 3" inside diameter, at base, and the rule of thumb is to reduce the line pull about (10%) for ever layer (depending on the number of layers),

what would be the estimated line pull, any one have the formula to figure,

what I am wanting to figure is how much drill torque is to guesstimate the line pull


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Is this correct, say the 30 pounds of pull on the drill at 12" from chuck, that 30 FP x 50 reduction, would be 1500 Foot Pounds on the main shaft,, the 3" diameter would be a 1/4 of 12 inches or a foot, (translating foot pounds), so the 1500 FP x 4 would be about, 6000 pounds of pull on first layer,
(as in the picture there is a number layers on the winch, guessing there is 6" diameter so the pull as the picture is would be about 3000 pounds of pull, (not taking into account for friction and other losses.)

is that correct?

 

[Baby Grand]

Your calculation looks good to me. You will definitely lose say 10% to friction in the gear reduction.

You can also get a pretty accurate measure of the drill's torque by hanging a bucket off the end of the line and fill it with water 'til the drill won't lift it (don't burn out your drill!). Then weigh the bucket of water and multiply that by the radius from drill center to line center (in inches) and divide that by 12 to get torque in lbs-ft.

 

[Travelover]

To estimate the drill's torque, couldn't you just attach it to a mechanical torque wrench and see how far it moves the needle?

 

[Nuno]

don't know if this Tool can be helpful because it is written in German but it is especially for Winch Calculations,

http://www.mein-woodworking.de/winde.html

maybe you can translate it or if you want, i can help to translate

 

[MillWeld]

the rule of thumb is to reduce the line pull about (10%) for ever layer (depending on the number of layers),

You should really do the calculation for each layer on the drum instead of the 10% rule. The drum radius increases by one diameter of the wire rope for each layer on the drum. As you know, when you get 6 or 7 layers the pull dramatically falls.

 

[BHD]

Thank you all for your comments and recommendations,

my main concern was not that what I was wanting to lift was to heavy, but so I did not stress any other items or the cable if some thing gets caught, in the process, and If I am hand holding the drill, and have a idea of the max I could be applying to the pull, then I know I am with in my safety limits, of the cable, (I was considering powering with a hydraulic motor, but have decided against it as I would not have any check on the power it was producing (made a similar unit for my son, and at first he had a few failures on the cable as he pulled it into, until he changed the chain sprockets that were between the motor and the gear box, (he was using 1/2 cable) I am going to be using 3/8" cable, so I want to make sure that I do not over power the cable if some thing gets caught or not goes correctly the Item I am lifting will be only less than 500 pounds,

 

[BHD]

don't know if this Tool can be helpful because it is written in German but it is especially for Winch Calculations,

Seilwinde

maybe you can translate it or if you want, i can help to translate

I looked it up on Google and use Google to translate it thanks,